System for gaseous fuel ignition for a cooking appliance

ABSTRACT

An improved ignition system is provided for use with a gaseous fuel burner on a cooktop of an appliance. A flame sensor is used to detect the presence of a flame at the gaseous fuel burner. When the flame is detected as absent for at least a certain predetermined period of time, the ignition system attempts to reignite the flame. During the predetermined time period, the ignition system does not attempt to reignite the flame even though the flame is not detected. As such, the flame has an opportunity to restore itself fully around the burner during the predetermined time period before the ignition system is activated.

The subject matter of the present disclosure relates generally to a system for igniting a gaseous fuel burner of an appliance.

BACKGROUND OF THE INVENTION

Cooking appliances are available that use a gaseous fuel in order to create heat for cooking food items. Such appliances include ovens, ranges, cook-tops, and others. Certain consumers may prefer the use of gaseous fuel over the use of e.g., electrically powered heating elements. Gaseous fuels that are commonly used include natural gas and propane.

For cooktop appliances that use gaseous fuel, typically at least one burner is provided with means for supporting a cooking utensil over the burner. Gas flow is controlled by a valve and an igniter is used to provide a spark so as to initiate combustion of the gaseous fuel. Conventionally, the user turns a knob to a position that opens the valve for gas flow through the burner and, at the same time, causes the igniter to begin emitting sparks at a location adjacent to the burner. Once the gaseous fuel is ignited, the user turns the knob to the desired heat setting and the igniter stops generating sparks.

Certain problems can occur when the gas burner is placed at its lowest heat setting. Typically, such low heat setting substantially reduces the flow of gaseous fuel and, therefore, the size of the flame at the burner. The flame is particularly susceptible to wafting and disturbances from local air currents while at the lower heat settings. For example, opening or closing a door on the appliance, the movement of air currents through the kitchen, and/or other events can cause the flame to fluctuate or flicker more readily at low gas flow. Even without such disturbances, at low gas flow the flame can be prone to wafting at one or more locations around the burner.

Sometimes one or more of these disruptive events may cause the flame to be extinguished at all locations around the burner. For certain cooking appliances, when the flame goes out completely while the burner is still supplied with fuel, the appliance may be equipped to restart the igniter. This automatic restart provides one or more sparks that will relight and restore the flame around the burner.

However, sometimes the flame may not be completely extinguished at all locations around the burner. Instead, particularly when the burner is at a low heat setting, only a portion of the desired flame around the burner may be absent due to wafting or other disturbances previously mentioned. In such situations, the absence of a portion of the flame may be only temporary, and the flame may eventually fully restore itself around the burner without the need for additional sparking from the igniter.

Nevertheless, with certain conventional systems, even the temporary absence of only a portion of the flame may cause the igniter to begin sparking until the flame is fully restored. Sparking provided by the igniter typically generates a sound that is perceptible to a user of the appliance. The sparking will repeat until the flame is fully restored. Because the flame is more susceptible to disruption at low gas flow as previously mentioned, such unnecessary sparking can become particularly bothersome or annoying to a user attempting to use the low heat settings. Such unwanted sparking is referred to herein as “nuisance sparking.”

Accordingly, an improved ignition system for a gaseous fuel burner of an appliance is needed. More particularly, an ignition system for a gaseous fuel burner of a cooktop appliance that can reduce or eliminate nuisance sparking would be beneficial.

BRIEF DESCRIPTION OF THE INVENTION

The present invention provides an improved ignition system for use with a gaseous fuel burner on a cooktop of an appliance. A flame sensor is used to detect the presence of a flame at the gaseous fuel burner. When the flame is detected as absent for at least a certain predetermined period of time, the ignition system attempts to reignite the flame. During the predetermined time period, the ignition system does not attempt to reignite the flame even though the flame is not detected. As such, the flame has an opportunity to restore itself fully around the burner during the predetermined time period before the ignition system is activated. The length of the predetermined time period is selected to minimize re-ignition attempts when the flame is only partially extinguished and, therefore, likely to restore itself. Additional aspects and advantages of the invention will be set forth in part in the following description, or may be apparent from the description, or may be learned through practice of the invention.

In one exemplary aspect, the present invention provides a method for igniting a gas burner. This exemplary method includes the steps of providing a gaseous fuel to the burner; operating an ignition system to ignite the gaseous fuel to the burner; detecting whether a flame is present at the burner over at least a first time period Δt₁. If so detected, then this exemplary method includes determining, after a flame has been detected at the burner for a time period Δt₁, whether a flame is absent from at least a portion of the burner over at least a second time period Δt₂, and, if so, then repeating the steps of operating and detecting.

In another exemplary embodiment, the present invention provides an ignition system for a cooking appliance using a gaseous fuel. The system includes a gas burner configured for the receipt of gaseous fuel. A valve is connected to a gas supply and is configured for controlling the flow of gaseous fuel to the gas burner. An ignition system is configured for igniting the gaseous fuel supplied to the gas burner. A flame sensor is configured for detecting the presence of a flame at the gas burner. At least one controller is configured for activating the ignition system to light the gaseous fuel at the burner; detecting whether a flame is present at the burner over at least a first time period Δt₁. If so detected, then the at least one controller is configured for determining, after the flame has been detected at the burner for the time period Δt₁, whether a flame is absent from at least a portion of the burner over at least a second time period Δt₂, and, if so, then repeating the steps of activating, detecting, and determining

These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:

FIG. 1 provides a perspective view of an exemplary embodiment of a cooktop appliance as may be used with the present invention.

FIG. 2 provides a schematic of an exemplary system for gaseous fuel ignition for a burner of a cooking appliance.

FIG. 3 illustrates an exemplary method of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.

FIG. 1 illustrates an exemplary embodiment of a cooktop appliance 100 as may be employed with the present subject matter. The present invention is not limited to use with a cooktop appliance such as that shown in FIG. 1, however. More particularly, cooktop appliance 100 shown in FIG. 1 illustrates an exemplary embodiment of the present subject matter. The present subject matter may be used in cooktop appliances having other configurations, e.g., a cooktop appliance with one, two, or more additional burner assemblies. Similarly, the present subject matter may be used in cooktop appliances that are part of a range or oven appliance as well as other cooking appliance configurations having a gas burner on a cooktop as well.

Cooktop appliance 100 includes a top panel 104. By way of example, top panel 104 may be constructed of glass, ceramics, enameled steel, and combinations thereof. For cooktop appliance 100, a utensil holding food and/or cooking liquids (e.g., oil, water, etc.) may be placed onto grates 116 at the location of any of burner assemblies 106, 108, 109, and 110. Burners assemblies 106, 108, 109, and 110 can be configured in various sizes so as to provide e.g., for the receipt of cooking utensils (i.e., pots, pans, etc.) of various sizes and configurations and to provide different heat inputs for such cooking utensils. Grates 116 are supported on a top surface 118 of top panel 104.

Burner assemblies 106, 108, 109, and 110 provide thermal energy to cooking utensils on grates 116. In particular, burner assemblies 106, 108, 109, and 110 extend through top panel 104 below grates 116. Burner assemblies 106, 108, 109, and 110 can also be mounted to top panel 104.

A user interface panel 112 is located within convenient reach of a user of cooktop appliance 100. For this exemplary embodiment, panel 112 includes knobs 114 that are each associated with one of burner assemblies 106, 108, 109, and 110. Knobs 114 are rotatable so as to allow the user to activate each burner assembly and determine the amount of heat input provided by each burner assembly 106, 108, 109, and 110 to a cooking utensil located thereon. Panel 112 may also be provided with one or more graphical display devices that deliver certain information to the user such as e.g., whether a particular burner assembly is activated and/or the level at which the burner assembly is set.

Although shown with knobs 114, it should be understood that knobs 114 and the configuration of cooktop appliance 100 shown in FIG. 1 are provided by way of example only. More specifically, user interface 112 may include various input components, such as one or more of a variety of touch-type controls, electrical, mechanical or electro-mechanical input devices including rotary dials, push buttons, and touch pads. The user interface 112 may include other display components, such as a digital or analog display device designed to provide operational feedback to a user.

An exemplary embodiment of a system 200 for gaseous fuel ignition of the present invention is illustrated schematically in FIG. 2. As shown, knob 114 is used to manipulate a valve 220 that controls the flow 216 of a gaseous fuel from supply 222. For example, knob 114 may be connected mechanically with valve 220 by a rod or shaft whereby the rotation of knob 114 determines the position of valve 220 between off, ignite, low, medium, and high settings. Alternatively, valve 220 may be continuously adjustable between a low and high setting so as to include multiple positions therebetween. Other configurations may be used as well. Gas flows from valve 220 to a gaseous fuel burner 202 (which could be e.g., any one of burners 106, 108, 109, or 110) through flow path 218. One or more features for combining air with the gaseous fuel in the proper ratio for combustion may be provided along flow path 218 and/or at gas burner 202.

An ignition system 204 is provided for initiating combustion of the gaseous fuel when flowing from burner 202. A variety of configurations may be used for ignition system 204. For example, ignition system 204 may include an electrode positioned near a metal component of burner 202 proximate to where gaseous fuel exits one or more openings in burner 202. The electrode can be caused to generate a spark between the electrode and metal component. The spark can ignite the flow of gaseous fuel flowing from burner 202 if in the proper ratio with air for combustion.

Indicia 120 (FIG. 1) may be provided near knob 114 to indicate a “light” or “ignition” position into which knob 114 can be rotated from an off position so as to cause the electrode to continuously spark while gas is allowed to flow through valve 220. Once a flame is established at burner 202, knob 114 can be rotated to the desired heat setting.

Other configurations for the ignition system 204 of system 200 may also be used and are within the scope of the present invention. For example, in another exemplary embodiment, the user can rotate the knob 114 from an off position directly to the desired heat setting without having to position knob 114 at a “light” or “ignition” position. With knob 114 positioned at the desired heat setting, the ignition system 204 automatically begins to spark and continues sparking until a flame is established at burner 202 as discussed more fully below.

System 200 also includes a flame sensor 206 that can be used to determine the presence of a flame at burner 202. A variety of configurations can be used for flame sensor 206. For example, flame sensor 206 may include an electrode positioned in proximity to burner 202. Upon the presence of a flame, sensor 206 provides a signal that can be received e.g., by a controller 208. Other configurations for flame sensor 206 can be used as well. Alternatively, or in addition thereto, flame sensor 206 can provide a signal indicating the absence of a flame from at least a portion of burner 202.

At least one controller 208 is also provided as part of system 200. Controller 208 may include one or more memory devices and one or more microprocessors, such as a general or special purpose microprocessor operable to execute programming instructions or micro-control code associated with the operation of cooktop appliance 100. The memory may represent random access memory such as DRAM, or read only memory such as ROM or FLASH. In one embodiment, the processor executes programming instructions stored in memory. Such instructions may implement one or more exemplary methods as described herein. The memory may be a separate component from the processor or may be included onboard within the processor. Controller 208 may be connected with one or more power sources. Although shown as a separate feature in FIG. 2, it should be understood that controller 208 and ignition system 204 could be constructed integrally in the unit or package.

As shown, for this exemplary embodiment of system 200, controller 208 can be e.g., placed into communication with, or receive signals from valve 220, ignition system 204, flame sensor 206, knob 114, or combinations thereof. For example, lines 210 and 224 represent one or more signals between valve 220, knob 114, and controller 208 whereby controller 208 can determine the position of valve 220. Consequently, controller 208 can thereby detect whether gas flow to burner 202 has been activated so as to provide a flow of gaseous fuel thereto.

Similarly, line 212 represents one or more signals between controller 208 and ignition system 204 whereby e.g., controller 208 may activate or cause ignition system 204 to operate so to provide a spark at burner 202. Alternatively, or in addition thereto, line 212 may represent a signal that can be provided to controller 208 when ignition system 204 has been activated.

Line 214 represents one or more signals whereby e.g., controller 208 can detect whether a flame is present at burner 202. For example, flame sensor 206 can provide such signal upon flame detection. While only one flame sensor 206 is shown, multiple flame sensors may be used about burner 202 to detect the presence of flame at more than one location around the burner.

As will be understood by one of skill in the art using the teachings disclosed herein, lines 210, 212, 214, and/or 224 can represent electrical, mechanical, or electro-mechanical means by which such signals are provided between the respective devices. For example, each line may represent one or more wires as needed to provide a signal.

FIG. 3 illustrates an exemplary method 350 of the present invention that may be used with e.g., cooktop appliance 100 equipped with system 200. Method 350 is provided by way of example only. Other methods may be used as well—as will be understood by one of ordinary skill in the art using the teachings disclosed herein.

Continuing with FIG. 3, step 300 represents an off condition from which a user may start using appliance 100. Accordingly, from step 300, the user rotates knob 114 to a position that provides a gaseous fuel flow through lines 216 and 218 to burner 202 as indicated in step 302. Upon rotating knob 114 out of an off position to a desired heat setting (or an “ignition” setting), such is detected by controller 204, which can then activate or operate ignition system 204 (step 304) so as to provide a spark that ignites gaseous fuel at burner 202.

In an alternative embodiment for step 304, the rotation of knob 114 that is connected with valve 220 may activate ignition system 204 directly. Controller 208 can then detect whether ignition system 204 has been activated through one or more signals as indicated by line 212. Steps 302 and 304 may occur simultaneously.

Next, in step 306, controller 208 detects or monitors for the presence of a flame at burner 202 using flame sensor 206. As indicated by step 306, controller 208 detects whether a flame is present at burner 202. Once detected, controller 208 can then deactivate ignition system 204 as indicated by step 308.

In steps 310 and 312, controller 208 determines whether the flame has been present at burner 202 for at least a first time period Δt₁. Stated alternatively, controller 208 detects or determines whether a flame has been sustained at burner 202 continuously for at least a first time period Δt₁. Time period Δt₁ is selected e.g., as a time period sufficient to ensure that a flame is ignited and established at burner 202. For example, in one exemplary aspect of the invention, first time period Δt₁ is in the range of 0.5 second to 1.5 seconds. In another exemplary aspect of the invention, first time period Δt₁ is about 1 second. Other time periods may be used as well. Steps 306, 308, 310, and/or 312 may occur simultaneously or nearly so. In another exemplary aspect of the invention, controller 208 may not deactivate ignition system 204 until a flame has been detected at burner 202 for at least the first time period Δt₁.

If, before time period Δt₁ has elapsed, controller 208 determines that the flame is no longer detected at burner 202, then the controller 208 returns to step 304 to reactivate the ignition system and repeat the method.

Alternatively, if controller 208 does detect a flame at burner 202 for at least a time period Δt₁, then in step 314 controller 208 continues monitoring the presence of a flame at burner 202. For example, in step 314, controller 208 uses flame sensor 206 to monitor the flame previously established at burner 202 while burner 202 is used to heat or cook food. During such time, as previously described, the flame may be subject to disruption from e.g., air currents, wafting, etc. For example, as part of such cooking operations, the user may use knob 114 to adjust valve 220 so as to select a low heat setting requiring a low flow of gaseous fuel to burner 202. At this setting, the flame at burner 202 can be particularly subject to disruption as previously described.

Accordingly, in order to minimize or prevent nuisance sparking, in steps 314 and 316 the controller 208 continues to monitor or determine whether a flame is present at gas burner 202. If the flame sensor 206 indicates that a flame is no longer being detected over at least a portion of burner 202, then as part of step 316 the controller 208 is programmed to determine whether the flame is absent from the burner 202 for at least a predetermined second time period Δt₂. It should be understood that even though flame sensor 206 indicates a flame is no longer detected, the flame may only be partially absent around burner 202. Nevertheless, such partial absence can cause flame sensor 206 to provide a signal indicative of the absence of the flame. However, rather than immediately causing ignition system 204 to begin sparking, upon determining the absence of a flame, controller 208 initiates a timer (e.g., starting at time t_(o)) to determine how long the flame is detected as absent.

If, after time t_(o), the flame sensor 206 detects the presence of a flame within a time period after t_(o) that is less than the predetermined second time period Δt₂, then controller 208 continues monitoring the flame as in step 314. However, if after time t_(o), the flame sensor 206 does not detect the flame for at least a time period Δt₂, then controller 202 returns to step 304 and activates or operates ignition system 204 to relight burner 202 and repeat steps 306 through 316.

By providing the second time period Δt₂ before attempting to reignite, system 350 provides an opportunity for the flame to fully restore itself at burner 202 without operating ignition system 204. As such, system 350 can prevent or minimize nuisance sparking. In one exemplary embodiment of the present invention, predetermined time period Δt₂ may be in the range of about 2.5 seconds to about 3.5 seconds. In another exemplary embodiment, predetermined time period Δt₂ may be about 3 seconds. In still another exemplary embodiment, predetermined time period Δt₂ may be about 5 seconds. Other time periods for Δt₂ may be used as well.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. 

What is claimed is:
 1. A method for igniting a gas burner, the steps comprising: providing a gaseous fuel to the burner; operating an ignition system to ignite the gaseous fuel to the burner; detecting whether a flame is present at the burner over at least a first time period Δt₁ and, if so, then determining, after a flame has been detected at the burner for a first time period Δt₁, whether a flame is absent from at least a portion of the burner over at least a second time period Δt₂, and, if so, then repeating the steps of operating and detecting.
 2. A method for igniting a gas burner as in claim 1, further comprising the step of detecting whether a valve controlling gas flow to the burner has been activated so as to provide a gaseous fuel to the burner.
 3. A method for igniting a gas burner as in claim 1, further comprising the step of detecting whether the ignition system has been activated.
 4. A method for igniting a gas burner as in claim 1, wherein the first time period Δt₁ is about one second.
 5. A method for igniting a gas burner as in claim 1, wherein the first time period Δt₁ is in the range of about 0.5 second to about 1.5 seconds.
 6. A method for igniting a gas burner as in claim 1, wherein the second time period Δt₂ is about 3 seconds.
 7. A method for igniting a gas burner as in claim 1, wherein the second time period Δt₂ is about 2.5 seconds to about 3.5 seconds.
 8. A method for igniting a gas burner as in claim 1, further comprising the steps of: stopping the flow of gaseous fuel to the burner; and ceasing the step of determining whether a flame is present at the burner.
 9. A method for igniting a gas burner as in claim 1, wherein the step of detecting whether a flame is present comprises monitoring a signal from a flame sensor positioned at the burner.
 10. A method for igniting a gas burner as in claim 1, wherein the step of determining whether a flame is absent from at least a portion of the burner comprises monitoring a signal from a flame sensor positioned at the burner.
 11. A method for igniting a gas burner as in claim 1, further comprising the steps of: determining whether gaseous fuel is provided to the burner and whether the ignition system is operating and, if so, then executing said step of detecting whether a flame is present at the burner over at least a first time period Δt₁.
 12. A method for igniting a gas burner as in claim 1, further comprising the step of deactivating the ignition system if a flame is present at the burner.
 13. A method for igniting a gas burner as in claim 1, further comprising the step of continuing to operate the ignition system during the first time period Δt₁.
 14. An ignition system for a cooking appliance using a gaseous fuel, comprising: a gas burner configured for the receipt of gaseous fuel; a valve connected to a gas supply and configured for controlling the flow of gaseous fuel to the gas burner; an ignition system configured for igniting the gaseous fuel supplied to the gas burner; a flame sensor configured for detecting the presence of a flame at the gas burner; at least one controller configured for activating the ignition system to light the gaseous fuel at the burner; detecting whether a flame is present at the burner over at least a first time period Δt₁ and, if so detected, then determining, after a flame has been detected at the burner for a first time period Δt₁, whether a flame is absent from at least a portion of the burner over at least a second time period Δt₂, and, if so, then repeating the steps of activating, detecting, and determining.
 15. An ignition system for a cooking appliance using a gaseous fuel as in claim 14, wherein the at least one controller is further configured for continuing operation of the ignition system during the step of detecting whether a flame is present at the burner over at least the first time period Δt₁.
 16. An ignition system for a cooking appliance using a gaseous fuel as in claim 14, wherein the first time period Δt₁ is about one second.
 17. An ignition system for a cooking appliance using a gaseous fuel as in claim 14, wherein the first time period Δt₁ is about 0.5 second to about 1.5 seconds.
 18. An ignition system for a cooking appliance using a gaseous fuel as in claim 14, wherein the second time period Δt₂ is about 3 seconds.
 19. An ignition system for a cooking appliance using a gaseous fuel as in claim 14, wherein the second time period Δt₂ is about 2.5 seconds to about 3.5 seconds.
 20. An ignition system for a cooking appliance using a gaseous fuel as in claim 14, wherein the second time period Δt₂ is about 5 seconds. 